We will evaluate synovial biopsies from rheumatoid arthritis (RA) patients and salivary gland biopsies from patients with Sjogren's Syndrome (SS) for the presence of retroviruses. Joint synovia and infiltrating lymphocytes from patients with RA and osteoarthritis and labial salivary gland biopsies from patients with SS will be grown in tissue culture for 7-30 days. Supernatants from cultured synovia and labial salivary glands will be precipitated with polyethylene glycol, and precipitates will be tested for the presence of reverse transcriptase using oligo A/dT and oligo C/dU template-primer hybrids and differing Concentrations of either Mn+2 or Mg+2. Cultured tissues will be examined by electron microscopy for the presence of type C and type A retroviral particles. Cultured synovia, infiltrative T-cells and salivary gland tissue will be treated with promo deoxyuridine and 5-iododeoxyuridine and then examined for induced expression of retroviral particles by electron microscopy and by reverse transcriptase assay. Tissues will be tested in indirect immunofluorescence and immunoperoxidase assays with anti-retroviral antibodies to HIV-1, HTLV-I and human endogenous retroviruses for expression of retroviral core and reverse transcriptase proteins. DNA and RNA from cultured synovia and salivary gland explants will be amplified by PCR or RT-PCR techniques using oligonucleotide probes containing consensus sequences of reverse transcriptase found in human and animal retroviruses. Amplified DNA will be sequenced and resulting sequences will be compared to known sequences. Amplified sequences will be used as probes to identify larger homologous sequences in human DNA. If present, type A and type C retroviral particles from tissue cultures will be purified by ultra centrifugation on sucrose density gradients and evaluated for RT activity and antigenic relatedness to other known human and animal retroviruses.